Dynamic bandwidth allocation to transmit a wireless protocol across a code division multiple access (CDMA) radio link

ABSTRACT

A technique for transmission of wireless signals across CDMA radio links. Bandwidth is allocated dynamically within a session to specific CDMA subscriber unit based upon data rate determinations. Specifically, a dynamic bandwidth allocation algorithm operates from limits calculated based upon available ports per subscriber, expected user bandwidth, and parallel user bandwidth versus throughput. Provisions for priority service, unbalanced forward and reverse spectrum utilization, voice prioritization, and band switching are also made.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of a prior pending U.S. ProvisionalApplication No. 60/050,338 filed Jun. 20, 1997 entitled "DynamicBandwidth Allocation to Transmit a Wireless ISDN Protocol Across a CodeDivision Multiple Access (CDMA) Radio Link" and a prior pending U.S.Provisional Application No. 60/050,277 filed Jun. 20, 1997 entitled"Protocol Conversion and Bandwidth Reduction Technique ProvidingMultiple nB+D ISDN Basic Rate Interface Links Over a Wireless CodeDivision Multiple Access Communication System."

BACKGROUND OF THE INVENTION

The increasing use of wireless telephones and personal computers by thegeneral population has led to a corresponding demand for advancedtelecommunication services that were once thought to only be meant foruse in specialized applications.

For example, in the late 1980's, wireless voice communication such asavailable with cellular telephony had been the exclusive province of thebusinessman because of expected high subscriber costs. The same was alsotrue for access to remotely distributed computer networks, whereby untilvery recently, only business people and large institutions could affordthe necessary computers and wireline access equipment.

However, the general population now increasingly wishes to not only haveaccess to networks such as the Internet and private intranets, but alsoto access such networks in a wireless fashion as well. This isparticularly of concern for the users of portable computers, laptopcomputers, hand-held personal digital assistants and the like who wouldprefer to access such networks without being tethered to a telephoneline.

There still is no widely available satisfactory solution for providinglow cost, high speed access to the Internet and other networks usingexisting wireless networks. This situation is most likely an artifact ofseveral unfortunate circumstances. For example, the typical manner ofproviding high speed data service in the business environment over thewireline network is not readily adaptable to the voice grade serviceavailable in most homes or offices. In addition, such standard highspeed data services do not lend themselves well to efficienttransmission over standard cellular wireless handsets.

Furthermore, the existing cellular network was originally designed onlyto deliver voice services. At present, the wireless modulation schemesin use continue their focus on delivering voice information with maximumdata rates only in the range of 9.6 kbps being readily available. Thisis because the cellular switching network in most countries, includingthe United States, uses analog voice channels having a bandwidth fromabout 300 to 3600 Hertz. Such a low frequency channel does not lenditself directly to transmitting data at rates of 28.8 kilobits persecond (kbps) or even the 56.6 kbps that is now commonly available usinginexpensive wire line modems, and which rates are now thought to be theminimum acceptable data rates for Internet access.

Switching networks with higher speed building blocks are just now cominginto use in the United States. Although certain wireline networks,called Integrated Services Digital Networks (ISDN), capable of higherspeed data access have been known for a number of years, their costshave only been recently reduced to the point where they are attractiveto the residential customer, even for wireline service. Although suchnetworks were known at the time that cellular systems were originallydeployed, for the most part, there is no provision for providingISDN-grade data services over cellular network topologies.

ISDN is an inherently circuit switched protocol, and was, therefore,designed to continuously send bits in order to maintain synchronizationfrom end node to end node to maintain a connection. Unfortunately, inwireless environments, access to channels is expensive and there iscompetition for them; the nature of the medium is such that they areexpected to be shared. This is dissimilar to the usual wireline ISDNenvironment in which channels are not intended to be shared bydefinition.

SUMMARY OF THE INVENTION

The present invention provides high speed data and voice service overstandard wireless connections via an unique integration of ISDNprotocols and existing cellular signaling such as is available with CodeDivision Multiple Access (CDMA) type modulated systems. The presentinvention achieves high data rates through more efficient allocation ofaccess to the CDMA wireless channels. In particular, a number ofsubchannels are defined within a standard CDMA channel bandwidth, whichis normally necessary to support the ISDN protocol, such as by assigningdifferent codes to each subchannel. The instantaneous bandwidth needs ofeach on-line subscriber unit are met by dynamically allocating multiplesubchannels of the RF carrier on an as needed basis for each session.For example, multiple subchannels are granted during times when thesubscriber bandwidth requirements are relatively high, such as whendownloading Web pages and released during times when the line content isrelatively light, such as when the subscriber is reading a Web pagewhich has been previously downloaded or is performing other tasks.

Subchannel assignment algorithms may be implemented to offer variouslevels of priority service to particular subscribers. These may beassigned based upon available ports per subscriber, expected userbandwidth, service premium payments, and so on.

In accordance with another aspect of the invention, some portion of theavailable bandwidth is initially allocated to establish a communicationsession. Once the session has been established, if a subscriber unit hasno data to present for transmission, namely, if the data path remainsquiescent for some period of time, the previously assigned bandwidth isdeallocated. In addition, it is preferable that not all of thepreviously assigned bandwidth be deallocated, but rather at least someportion be kept available for use by an in-session subscriber. If theinactivity continues for a further period of time, then even theremaining portion of the bandwidth can be deallocated from the session.A logical session connection at a network layer protocol is stillmaintained even if no subchannels are assigned.

In a preferred arrangement, a single subchannel is maintained for apredetermined minimum idle time for each network layer connection. Thisassists with more efficient management of channel setup and tear down.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the following more particulardescription of preferred embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views.

FIG. 1 is a block diagram of a wireless communication system making useof a bandwidth management scheme according to the invention.

FIG. 2 is an Open System Interconnect (OSI) type layered protocoldiagram showing where the bandwidth management scheme is implemented interms of communication protocols.

FIG. 3 is a diagram showing how subchannels are assigned within a givenradio frequency (RF) channel.

FIG. 4 is a more detailed block diagram of the elements of a subscriberunit.

FIG. 5 is a state diagram of the operations performed by a subscriberunit to request and release subchannels dynamically.

FIG. 6 is a block diagram of a portion of a base station unit necessaryto service each subscriber unit.

FIG. 7 is a high level structured English description of a processperformed by the base station to manage bandwidth dynamically accordingto the invention.

DETAILED DESCRIPTION OF THE INVENTION

Turning attention now to the drawings more particularly, FIG. 1 is ablock diagram of a system 100 for providing high speed data and voiceservice over a wireless connection by seamlessly integrating a digitaldata protocol such as, for example, Integrated Services Digital Network(ISDN) with a digitally modulated wireless service such as Code DivisionMultiple Access (CDMA).

The system 100 consists of two different types of components, includingsubscriber units 101, 102 and base stations 170. Both types of thesecomponents 101 and 170 cooperate to provide the functions necessary inorder to achieve the desired implementation of the invention. Thesubscriber unit 101 provides wireless data services to a portablecomputing device 110 such as a laptop computer, portable computer,personal digital assistant (PDA) or the like. The base station 170cooperates with the subscriber unit 101 to permit the transmission ofdata between the portable computing device 110 and other devices such asthose connected to the Public Switched Telephone Network (PSTN) 180.

More particularly, data and/or voice services are also provided by thesubscriber unit 101 to the portable computer 110 as well as one or moreother devices such as telephones 112-1, 112-2 (collectively referred toherein as telephones 112. (The telephones 112 themselves may in turn beconnected to other modems and computers which are not shown in FIG. 1).In the usual parlance of ISDN, the portable computer 110 and telephones112 are referred to as terminal equipment (TE). The subscriber unit 101provides the functions referred to as a network termination type 1(NT-1). The illustrated subscriber unit 101 is in particular meant tooperate with a so-called basic rate interface (BRI) type ISDN connectionthat provides two bearer or "B" channels and a single data or "D"channel with the usual designation being 2B+D.

The subscriber unit 101 itself consists of an ISDN modem 120, a devicereferred to herein as the protocol converter 130 that performs thevarious functions according to the invention including spoofing 132 andbandwidth management 134, a CDMA transceiver 140, and subscriber unitantenna 150. The various components of the subscriber unit 101 may berealized in discrete devices or as an integrated unit. For example, anexisting conventional ISDN modem 120 such as is readily available fromany number of manufacturers may be used together with existing CDMAtransceivers 140. In this case, the unique functions are providedentirely by the protocol converter 130 which may be sold as a separatedevice. Alternatively, the ISDN modem 120, protocol converter 130, andCDMA transceiver 140 may be integrated as a complete unit and sold as asingle subscriber unit device 101.

The ISDN modem 120 converts data and voice signals between the terminalequipment 110 and 112 to format required by the standard ISDN "U"interface. The U interface is a reference point in ISDN systems thatdesignates a point of the connection between the network termination(NT) and the telephone company.

The protocol converter 130 performs spoofing 132 and basic bandwidthmanagement 134 functions, which will be described in greater detailbelow. In general, spoofing 132 consists of insuring that the subscriberunit 101 appears to the terminal equipment 110, 112 that is connected tothe public switched telephone network 180 on the other side of the basestation 170 at all times.

The bandwidth management function 134 is responsible for allocating anddeallocating CDMA radio channels 160 as required. Bandwidth managementalso includes the dynamic management of the bandwidth allocated to agiven session by dynamically assigning sub-portions of the CDMA channels160 in a manner which is more fully described below.

The CDMA transceiver 140 accepts the data from the protocol converter130 and reformats this data in appropriate form for transmission througha subscriber unit antenna 150 over CDMA radio link 160-1. The CDMAtransceiver 140 may operate over only a single 1.25 MHZ radio frequencychannel or, alternatively, in a preferred embodiment, may be tunableover multiple allocatable radio frequency channels.

CDMA signal transmissions are then received at the base station andprocessed by the base station equipment 170. The base station equipment170 typically consists of multichannel antennas 171, multiple CDMAtransceivers 172, and a bandwidth management functionality 174.Bandwidth management controls the allocation of CDMA radio channels 160and subchannels. The base station 170 then couples the demodulated radiosignals to the Public Switch Telephone Network (PSTN) 180 in a mannerwhich is well known in the art. For example, the base station 170 maycommunicate with the PSTN 180 over any number of different efficientcommunication protocols such as primary rate ISDN, or other LAPD basedprotocols such as IS-634 or V5.2.

It should also be understood that data signals travel bidirectionallyacross the CDMA radio channels 160, i.e., data signals originate at theportable computer 110 are coupled to the PSTN 180, and data signalsreceived from the PSTN 180 are coupled to the portable computer 110.

Other types of subscriber units such as unit 102 may be used to providehigher speed data services. Such subscriber units 102 typically providea service referred to as nB+D type service that may use a so-calledPrimary Rate Interface (PRI) type protocol to communicate with theterminal equipment 110, 112. These units provide a higher speed servicesuch as 512 kbps across the U interface. Operation of the protocolconverter 130 and CDMA transceiver 140 are similar for the nB+D typesubscriber unit 102 as previously described for subscriber unit 101,with the understanding that the number of radio links 160 to supportsubscriber unit 102 are greater in number or each have a greaterbandwidth.

Turning attention now to FIG. 2, the invention may be described in thecontext of a Open Systems Interconnect multilayer protocol diagram. Thethree protocol stacks 220, 230, and 240 are for the ISDN modem 120,protocol converter 130, and base station 170, respectively.

The protocol stack 220 used by the ISDN modem 120 is conventional forISDN communications and includes, on the terminal equipment side, theanalog to digital conversion (and digital to analog conversion) 221 anddigital data formatting 222 at layer one, and an applications layer 223at layer two. On the U interface side, the protocol functions includeBasic Rate Interface (BRI) such as according to standard 1.430 at layerone, a LAPD protocol stack at layer two, such as specified by standardQ.921, and higher level network layer protocols such as Q.931 or X.227and high level end to end signaling 228 required to establish networklevel sessions between modes.

The lower layers of the protocol stack 220 aggregate two bearer (B)channels to achieve a single 128 kilobits per second (kbps) data rate ina manner which is well known in the art. Similar functionality can beprovided in a primary rate interface, such as used by subscriber unit102, to aggregate multiple B channels to achieve up to 512 kbps datarate over the U interface.

The protocol stack 230 associated with the protocol converter 130consists of a layer one basic rate interface 231 and a layer two LAPDinterface 232 on the U interface side, to match the corresponding layersof the ISDN modem stack 220.

At the next higher layer, usually referred to as the network layer, abandwidth management functionality 235 spans both the U interface sideand the CDMA radio link side of the protocol converter stack 230. On theCDMA radio link side 160, the protocol depends upon the type of CDMAradio communication in use. An efficient wireless protocol referred toherein as EW[x] 234, encapsulates the layer one 231 and layer two 232ISDN protocol stacks in such a manner that the terminal equipment 110may be disconnected from one or more CDMA radio channels withoutinterrupting a higher network layer session.

The base station 170 contains the matching CDMA 241 and EW[x] 242protocols as well as bandwidth management 243. On the PSTN side, theprotocols may convert back to basic rate interface 244 and LAPD 245 ormay also include higher level network layer protocols as Q.931 or V5.2246.

Call processing functionality 247 allows the network layer to set up andtear down channels and provide other processing required to support endto end session connections between nodes as is known in the art.

The spoofing function 132 performed by the EW[x] protocol 234 includesthe necessary functions to keep the U interface for the ISDN connectionproperly maintained, even in the absence of a CDMA radio link 160 beingavailable. This is necessary because ISDN, being a protocol originallydeveloped for wire line connections, expects to send a continuous streamof synchronous data bits regardless of whether the terminal equipment ateither end actually has any data to transmit. Without the spoofingfunction 132, radio links 160 of sufficient bandwidth to support atleast a 192 kbps data rate would be required throughout the duration ofan end to end network layer session, whether or not data is actuallypresented.

EW[x] 234 therefore involves having the CDMA transceiver 140 loop backthese synchronous data bits over the ISDN communication path to spoofthe terminal equipment 110, 112 into believing that a sufficiently widewireless communication link 160 is continuously available. However, onlywhen there is actually data present from the terminal equipment to thewireless transceiver 140 is wireless bandwidth allocated. Therefore,unlike the prior art, the network layer need not allocate the assignedwireless bandwidth for the entirety of the communications session. Thatis, when data is not being presented upon the terminal equipment to thenetwork equipment, the bandwidth management function 235 deallocatesinitially assigned radio channel bandwidth 160 and makes it availablefor another transceiver and another subscriber unit 101.

In order to better understand how bandwidth management 235 and 243accomplish the dynamic allocation of radio bandwidth, turn attention nowto FIG. 3. This figure illustrates one possible frequency plan for thewireless links 160 according to the invention. In particular, a typicaltransceiver 170 can be tuned on command to any 1.25 MHZ channel within amuch larger bandwidth, such as up to 30 MHZ. In the case of location inan existing cellular radio frequency bands, these bandwidths aretypically made available in the range of from 800 to 900 MHZ. Forpersonal communication systems (PCS) type wireless systems, thebandwidth is typically allocated in the range from about 1.8 to 2.0GigaHertz (GHz). In addition, there are typically two matching bandsactive simultaneously, separated by a guard band, such as 80 MHZ; thetwo matching bands form forward and reverse full duplex link.

Each of the CDMA transceivers, such as transceiver 140 in the subscriberunit 101 and transceivers 172 in the base station 170, are capable ofbeing tuned at any given point in time to a given 1.25 MHZ radiofrequency channel. It is generally understood that such 1.25 MHZ radiofrequency carrier provides, at best, a total equivalent of about 500 to600 kbps maximum data rate transmission within acceptable bit error ratelimitations.

In the prior art, it was thus generally understood that in order tosupport an ISDN type like connection which may contain information at arate of 128 kbps that, at best, only about (500 kbps/128 kbps) or only 3ISDN subscriber units could be supported at best.

In contrast to this, the present invention subdivides the availableapproximately 500 to 600 kbps bandwidth into a relatively large numberof subchannels. In the illustrated example, the bandwidth is dividedinto 64 subchannels 300, each providing an 8 kbps data rate. A givensubchannel 300 is physically implemented by encoding a transmission withone of a number of different assignable pseudorandom codes. For example,the 64 subchannels 300 may be defined within a single CDMA RF carrier byusing a different orthogonal Walsh codes for each defined subchannel300.

The basic idea behind the invention is to allocate the subchannels 300only as needed. For example, multiple subchannels 300 are granted duringtimes when a particular ISDN subscriber unit 101 is requesting thatlarge amounts of data be transferred. These subchannels 300 are releasedduring times when the subscriber unit 101 is relatively lightly loaded.

Before discussing how the subchannels are preferably allocated anddeallocated, it will help to understand a typical subscriber unit 101 ingreater detail. Turning attention now to FIG. 4, it can be seen that anexemplary protocol converter 130 consists of a microcontroller 410,reverse link processing 420, and forward link processing 430. Thereverse link processing 420 further includes ISDN reverse spoofer 422,voice data detector 423, voice decoder 424, data handler 426, andchannel multiplexer 428. The forward link processing 430 containsanalogous functions operating in the reverse direction, including achannel multiplexer 438, voice data detector 433, voice decoder 434,data handler 436, and ISDN forward spoofer 432.

In operation, the reverse link 420 first accepts channel data from theISDN modem 120 over the U interface and forwards it to the ISDN reversespoofer 432. Any repeating, redundant "echo" bits are removed from datareceived and, once extracted, sent to the forward spoofer 432. Theremaining layer three and higher level bits are thus information thatneeds to be send over a wireless link.

This extracted data is sent to the voice decoder 424 or data handler426, depending upon the type of data being processed.

Any D channel data from the ISDN modem 120 is sent directly to voicedata detection 423 for insertion on the D channel inputs to the channelmultiplexer 428. The voice data detection circuit 423 determines thecontent of the D channels by analyzing commands received on the Dchannel.

D channel commands may also be interpreted to control a class ofwireless services provided. For example, the controller 410 may store acustomer parameter table that contains information about the customersdesired class of service which may include parameters such as maximumdata rate and the like. Appropriate commands are thus sent to thechannel multiplexer 428 to request one or more required subchannels 300over the radio links 160 for communication. Then, depending upon whetherthe information is voice or data, either the voice decoder 424 or datahandler 426 begins feeding data inputs to the channel multiplexer 428.

The channel multiplexer 428 may make further use of control signalsprovided by the voice data detection circuits 423, depending uponwhether the information is voice or data.

In addition, the CPU controller 410, operating in connection with thechannel multiplexer 428, assists in providing the necessaryimplementation of the EW[x] protocol 234 between the subscriber unit 101and the base station 170. For example, subchannel requests, channelsetup, and channel tear down commands are sent via commands placed onthe wireless control channel 440. These commands are intercepted by theequivalent functionality in the base station 170 to cause the properallocation of subchannels 300 to particular network layer sessions.

The data handler 426 provides an estimate of the data rate required tothe CPU controller 410 so that appropriate commands can be sent over thecontrol channel 440 to allocate an appropriate number of subchannels.The data handler 426 may also perform packet assembly and buffering ofthe layer three data into the appropriate format for transmission.

The forward link 430 operates in analogous fashion. In particular,signals are first received from the channels 160 by the channelmultiplexer 438. In response to receiving information on the controlchannels 440, control information is routed to the voice data detectioncircuit 433. Upon a determination that the received information containsdata, the received bits are routed to the data handler 436.Alternatively, the information is voice information, and routed to thevoice decoder 434.

Voice and data information are then sent to the ISDN forward spoofer 432for construction into proper ISDN protocol format. This assembly ofinformation is coordinated with the receipt of echo bits from the ISDNreverse spoofer 422 to maintain the proper expected synchronization onthe U interface with the ISDN modem 120.

It can now be seen how a network layer communication session may bemaintained even though wireless bandwidth initially allocated fortransmission is reassigned to other uses when there is no information totransmit. In particular, the reverse 422 and forward 432 spooferscooperate to loop back non-information bearing signals, such as flagpatterns, sync bits, and other necessary information, so as to spoof thedata terminal equipment connected to the ISDN modem 120 into continuingto operate as though the allocated wireless path over the CDMAtransceiver 150 is continuously available.

Therefore, unless there is an actual need to transmit information fromthe terminal equipment being presented to the channel multiplexers 428,or actual information being received from the channel multiplexers 438,the invention may deallocate initially assigned subchannel 300, thusmaking them available for another subscriber unit 101 of the wirelesssystem 100.

The CPU controller 410 may also perform additional functions toimplement the EW[x] protocol 234, including error correction, packetbuffering, and bit error rate measurement.

The functions necessary to implement bandwidth management 235 in thesubscriber unit 101 are carried out in connection with the EW[x]protocol typically by the CPU controller 410 operating in cooperationwith the channel multiplexers 428, 438, and data handlers 420, 436. Ingeneral, bandwidth assignments are made for each network layer sessionbased upon measured short term data rate needs. One or more subchannels300 are then assigned based upon these measurements and other parameterssuch as amount of data in queue or priority of service as assigned bythe service provider. In addition, when a given session is idle, aconnection is preferably still maintained end to end, although with aminimum number of, such as a single subchannel being assigned. Forexample, this single subchannel may eventually be dropped after apredetermined minimum idle time is observed.

FIG. 5 is a detailed view of the process by which a subscriber unit 101may request subchannel 300 allocations from the base station 170according to the invention. In a first state 502, the process is in anidle state. At some point, data becomes ready to transmit and state 504is entered, where the fact that data is ready to be transmitted may bedetected by an input data buffer in the data handler 426 indicated thatthere is data ready.

In state 504, a request is made, such as via a control channel 440 forthe allocation of a subchannel to subscriber unit 101. If a subchannelis not immediately available, a pacing state 506 may be entered in whichthe subscriber unit simply waits and queues its request for a subchannelto be assigned.

Eventually, a subchannel 300 is granted by the base station and theprocess continues to state 508. In this state, data transfer may thenbegin using the single assigned subchannel. The process will continue inthis state as long as the single subchannel 300 is sufficient formaintaining the required data transfer and/or is being utilized.However, if the input buffer should become empty, such as notified bythe data handler 426, then the process will proceed to a state 510. Inthis state 510, the subchannel will remain assigned in the event thatdata traffic again resumes. In this case, such as when the input bufferbegins to once again become full and data is again ready to transmit,then the process returns to state 508. However, from state 510 should alow traffic timer expire, then the process proceeds to state 512 inwhich the single subchannel 300 is released. The process then returns tothe idle state 502. In state 512, if a queue request is pending fromstates 506 or 516, the subchannel is used to satisfy such requestinstead of releasing it.

Returning to state 508, if instead the contents of the input buffer arebeginning to fill at a rate which exceeds a predetermined thresholdindicating that the single subchannel 300 is insufficient to maintainthe necessary data flow, then a state 514 is entered in which moresubchannels 300 are requested. A subchannel request message is againsent over the control channel 440 or through a subchannel 300 alreadyallocated. If additional subchannels 300 are not immediately available,then a pacing state 516 may be entered and the request may be retried byreturning to state 514 and 516 as required. Eventually, an additionalsubchannel will be granted and processing can return to state 508.

With the additional subchannels being now available, the processingcontinues to state 518 where data transfer may be made on a multiple Nof the subchannels. This may be done at the same time through a channelbonding functional or other mechanism for allocating the incoming dataamong the N subchannels. As the input buffer contents reduced below anempty threshold, then a waiting state 520 may be entered.

If, however, a buffer filling rate is exceeded, then state 514 may beentered in which more subchannels 300 are again requested.

In state 520, if a high traffic timer has expired, then one or more ofthe additional subchannels are released in state 522 and the processreturns to state 508.

FIG. 6 is a block diagram of the components of the base stationequipment 170 of the system 100. These components perform analogousfunctions to those as already described in detail in FIG. 4 for thesubscriber unit 101. It should be understood that a forward link 620 andreverse link 630 are required for each subscriber unit 101 or 102needing to be supported by the base station 170.

The base station forward link 620 functions analogously to the reverselink 420 in the subscriber unit 100, including a subchannel inversemultiplexer 622, voice data detection 623, voice decoder 624, datahandler 626, and ISDN spoofer 622, with the understanding that the datais traveling in the opposite direction in the base station 170.Similarly, the base station reverse link 630 includes componentsanalogous to those in the subscriber forward link 430, including an ISDNspoofer 632, voice data detection 633, voice decoder 634, data handler636, and subchannel multiplexer 638. The base station 170 also requiresa CPU controller 610.

One difference between the operation of the base station 170 and thesubscriber unit 101 is in the implementation of the bandwidth managementfunctionality 243. This may be implemented in the CPU controller 610 orin another process in the base station 170.

A high level description of a software process performed by dynamicchannel allocation portion 650 of the bandwidth management 243 iscontained in FIG. 7. This process includes a main program 710, which iscontinuously executed, and includes processing port requests, processingbandwidth release, and processing bandwidth requests, and then locatingand tearing down unused subchannels.

The processing of port requests is more particularly detailed in a codemodule 720. These include upon receiving a port request, and reserving asubchannel for the new connection, preferably chosen from the leastutilized section of the radio frequency bandwidth. Once the reservationis made, an RF channel frequency and code assignment are returned to thesubscriber unit 101 and a table of subchannel allocations is updated.Otherwise, if subchannels are not available, then the port request isadded to a queue of port requests. An expected waiting time may beestimated upon the number of pending port requests and priorities, andan appropriate wait message can be returned to the requesting subscriberunit 101.

In a bandwidth release module 730, the channel bonding functionexecuting in the multiplexer 622 in the forward link is notified of theneed to release a subchannel. The frequency and code are then returnedto an available pool of subchannels and a radio record is updated.

The following bandwidth request module 740 may include electing therequest having the highest priority with lowest bandwidth utilization.Next, a list of available subchannels is analyzed for determining thegreatest available number. Finally, subchannels are assigned based uponneed, priority, and availability. A channel bandwidth bonding functionis notified within the subchannel multiplexer 622 and the radio recordwhich maintains which subchannels are assigned to which connections isupdated.

In the bandwidth on demand algorithm, probability theory may typicallybe employed to manage the number of connections or available ports, andthe spectrum needed to maintain expected throughput size and frequencyof subchannel assignments. There may also be provisions for priorityservice based upon subscribers who have paid a premium for theirservice.

It should be understood, for example, that in the case of a supporting128 kbps ISDN subscriber unit 101 that even more than 16×8 kbpssubchannels may be allocated at a given time. In particular, one mayallow a larger number, such as 20 subchannels, to be allocated tocompensate for delay and reaction in assigning subchannels. This alsopermits dealing with bursts of data in a more efficient fashion such astypically experienced during the downloading of Web pages.

In addition, voice traffic may be prioritized as against data traffic.For example, if a voice call is detected, at least one subchannel 300may be active at all times and allocated exclusively to the voicetransfer. In that way, voice calls blocking probability will beminimized.

EQUIVALENTS

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention as defined by the appended claims.

For example, instead of ISDN, other wireline digital protocols may beencapsulated by the EW[x] protocol, such as xDSL, Ethernet, and X.25,and therefore may advantageously use the dynamic wireless subchannelassignment scheme described herein.

Those skilled in the art will recognize or be able to ascertain using nomore than routine experimentation, many equivalents to the specificembodiments of the invention described specifically herein. Suchequivalents are intended to be encompassed in the scope of the claims.

What is claimed is:
 1. A method for providing wireless communication ofdigital data signals, the digital data signals being communicatedbetween a plurality of wireless subscriber units, and a base station,the digital signals being communicated using at least one radiofrequency channel via digitally modulated Code Division Multiple Access(CDMA) signals, the digitally modulated CDMA signals also having a givennominal data rate, the method comprising the steps of:a) makingavailable a plurality of subchannels within each CDMA radio channel,wherein a data rate of each subchannel is much less than the nominaldata rate of the digitally modulated CDMA radio signals; b) establishinga network layer session between terminal equipment connected to thesubscriber unit through the base station to other terminal equipmentconnected to the base station; and c) during the network layer session,allocating available subchannels only on an as needed basis, with thenumber of subchannels allocated thereby changing during the duration ofa given session and such that even when no digital signals are presentduring the session connection, subchannels are deallocated from theconnection while maintaining the appearance of a continuous sessionconnection at the network layer.
 2. A method as in claim 1 wherein aplurality of subchannels are made available on a single radio frequencycarrier by assigning orthogonal codes for each subchannel.
 3. A methodas in claim 1 wherein step b) additionally comprises:i) uponestablishing a network layer session, initially allocating a singlesubchannel; and ii) as a session requires additional bandwidth tomaintain transmission of the digital signals, allocating additionalsubchannels.
 4. A method as in claim 1 wherein the digital signalsinclude a digitized representation of a voice signal, additionallycomprising the step of:maintaining allocation of subchannels sufficientto service bandwidth requirements of the voice signal for the durationof the session connection.
 5. A method as in claim 1 wherein the digitalsignals include a digitized representation of a voice signal,additionally comprising the step of:selecting a subchannel bandwidth tobe sufficient to transmit the voice signal bandwidth continuously.
 6. Amethod as in claim 1 wherein step c) additionally comprises:spoofinglower physical layers at the subscriber unit into behaving as ifsufficient bandwidth is available to continuously transmit digitalsignals.
 7. A method as in claim 1 wherein subchannels are allocated ona priority class of service basis among a number of subscriber units. 8.A method as in claim 1 wherein the digital signals are of differentnominal bandwidths.